[JordanMix]

So i now have 120 miles on my rebuilt engine (new guides, seats ground, new piston, rings and barrel bored). I cant seem to get a plug read and i haven't been able to find any material or previous post on this. I was running a 130, 30 jet set up stock slide and needle on the second from the bottom clip. I was getting black plugs. So tonight i put in the 27.5, 130 and keep the needle at the second from the bottom clip. I am running a shorty exhaust with no baffle and a velocity stack so i am getting plenty of air flow. I also do not have a leak anywhere... all o rings, seal caps as well as the rubber intake have been replaced.

My question is.... does it take this long for rings to seat? i dont know if i am getting black plugs from oil or carbon ( i cant tell) but i can not get a read and i would think with the main jet switch it would show some difference. I am noticing some burping/hesitation at higher speeds like i am not getting enough fuel. I should also note that float height was just checked and is at 25MM.


from what i have read most people are running a  130, 30 jet set up with the clip on the lowest position and that is with a K&N filter usually. I have a velo stack which i would think allows in even more air. I should be seeing a whiter plug i would think.
here is a photo of my plug from tonight with about 15 miles on it.



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[JordanMix]

i forgot to mention that this was done at about 30 MPH after about 30 seconds. All the riding on this plus was back roads with very little start stop. I but the outside threads off completely to get a better view of the whole insulator.

[mtrude]

Plug reading can be tricky business. The condition of the plug will show the most recent conditions it was exposed to. I dont think a short ride around will show anything you can refer to. You really need a handful of new, gapped plugs, a clear stretch of road and some time to do it correctly. Get the engine warmed up well, put in a new plug and then ride it up to  a steady mid throttle condition, without lugging or over revving the engine, pull in the clutch and shut off the engine and coast to a stop, this plug would/should show your mid range jetting condition. start over with a fresh plug, this time accelerate at full throttle up to the a fair speed, ( thus the clear road) pull in the clutch, shut off the engine and, and pull over. This should show your main jet condition. Different engine loads will produce different readings. There are variations of this technique but this has worked for me. Tere was a previous post concerning fuel to the carb, make sure its getting there from the tank. Good luck, have fun, mtrude

[JordanMix]

after doing some more reseach this morning i am thinking i do have some blow by. I have experienced increased oil loss and have noticed oil on my back where and an over oiled chain from my crank case breather/duckbill. I have read that this is usually caused by cumbustion gasses getting past the rings into the crankcase causing to much pressure that needs to be released. If this is happening with the combustion gasses them oil must be getting past the rings as well.

Its just extremal frustrating to be going through the same problems again after all the money/time put into it. If the rings should have seated by now what should i do... throw another hundred plus dollars at the problem in new (higher quality) rings/piston and hope for the best?

thanks for your reply on plug reading. Once (if) i get the oil controll take care of i will take your advice on the plug reading.

[mtrude]

Hello, You could do a compression test to make sure there is a lack of ring sealing, If so , could you just pull the head and cylinder, use a hone or cloth to re-hatch the cylinder walls and reassemble? mtrude

[Vince]

     Other things can cause excess crank case pressure. Too much oil is the most common problem. Make sure the level is only about 1/2 way up the dipstick. Take off the breather hose(s) and blow them out thoroughly. Drain the oil separator if you are still running it it the breather system. Other issues I've run into are with machining. Is the bore straight and to tolerance? Are the rings installed properly. I have found customer installs with broken or up side down rings, or even rings in the wrong order.  I have found guide installation problems ranging from too loose to cracked guide or head. Check oil and breather system first, then go back into the engine. Good luck!

[JordanMix]

I am hoping the crankcase is due to an overfilled oil reservoir. I have been filling it up to just below the F line because it’s been going through so much. I will drain a little tonight and try to lean it out a bit more by raising the clip to the third position on the needle.

Vince.

I don’t know if the bore is straight or to tolerance. I do not know how to check for this. I know its stupid to assume, but is this something a proper machinist would have checked for? Could you elaborate on this? Also, is it possible to have a bottom end problem or to large of a wrist pin hole in the con arm? I am not experiencing piston slap (at least I do not hear any) but in the sake of exploring all avenues I didn’t know if this could also cause blow by.

Rings are installed properly… I made an extra point to check this. Large ring on the bottom, middle ring is the slightly less shiny ring installed with the side stamped “top” facing up and the top ring is slightly shiny and does not have an up or down side.

Mtrude.

I do want to perform a compression test but I don’t have the kit or a compressor and I have never witnessed one done. If the leaning out of the bike, lowering the oil level, and cleaning out my duckbill breather does not rectify my situation this will be my next step. I may just call around to mechanics to see if they will perform the test with me while I am there. I wouldn’t mind having the test kit but a compressor is not an option right now. The power supply is so weak to my garage that a mini shop vac throws the breaker, a air compressor would definitely trip it.

I have read that around 100 PSI is good… is this true. I don’t know what its worth but I weight about 165 pounds and the kick starter will hold me for about 1.5 seconds before it gives way.

[Vince]

     Your compression is probably fine. If a certified machinist did the work the bore is probably straight, but this can be easily checked with the proper tools upon disassembly. The test you should perform before tear down is a leak down test. The engine will have to be held at TDC on compression (with the valves closed). Then the cylinder is pressurized. A ring or guide problem will show up as an air leak. For instance, if you hear air the oil filler you have a ring problem. Air from the carb indicates an intake valve issue. A perfect motor has about 2 o/o leak down. pressurized at 100 lbs it should hold 98lbs. Generally up to 10o/o leak down is OK. 20o/o is real marginal. more is a dead engine. Any good shop can do this for you. The primary cover must be removed to put a wrench on the crank to hold it in position when pressurized. A blown or loose rod or crank will cause  problems of course. I assumed this was checked before assembly.

[Foggy_Auggie]

Mtrude has the plug reading for mid range correct.  It's called a "plug chop" - chopping (cutting) off the ignition, coasting to a stop and reading the plug right there.

I've only used full throttle plug chops.  Run full throttle (open country road) for about 3 minutes after the engine is at operating temperature.  I make the engine work by going up a long hill.

Do a plug chop and it should be medium coffee tan in color.

If the plug chop is O.K at full throttle - chances are the mid range is O'K. also for the jetting and plug heat range.

Checking the plug after pulling in the driveway - it will always look black.

[JordanMix]

Vince.

I wish my local RE dealer was 1/16 as helpful in person as you are over the internet. He wouldn’t work on my bike because of “serious modifications”… shortty exhaust, K&N filter and a duckbill breather. Needless to say that is the last time I will ever be in his dealership. I know these bikes are made to be worked on by the owner, but it is my belief if you are selling something that requires service over its life you should be able to and willing to do that service. I didn’t mention names here out of respect for everyone at CMW who have been great.


I am going to try a list of different items tonight/tomorrow and try to get it sorted out.

Just to get things straight a leak down test would diagnose poor ring sealing and worn guides? or just the rings sealing?

I read somewhere that you can test guides by removing the head and rocker covers and spraying a little carb cleaner at the top of each valve guide... place a paper towel under the head where the valve seats are and wait 5 minuets... if you have a leaky guide the cleaner will show on the paper towel. Does this sound like an accurate home method? It would seem like if you had a work guide but not a seating problem you wouldn’t get any drops to show.

If i cant get it sorted out this weekend i am going to order a leak down test from harbor freight for $30.00 (seems like a good deal) and pick up an air compressor. I have a power issue in my shop so i want to get the smallest one possible. Do you think a 1 HP, 2 or 4 gallon tank would work for this test? I could use a compressor anyway but i don’t need, nor can i afford to buy or supply power for the big ones.

I called a local cycle repair shop and asked about a leak down test and he said it would cost around $50 and they are booked for the next week (for an extra $100 I could buy a compressor and lookdown kit to have my own and learn a new skill.. think i will go that route). He was a nice guy though told me some things to check... much of which everyone has covered on here. He did mention that a tightly adjusted intake valve could be the problem but wouldn’t this show up as erratic backfiring, missing at all ranges?


Froggy/mtrude

i have preformed the proper plug chop and it looked almost identical to the plug photos i took of the plug after my ride home. I did about 4 chops on back roads, 2 of which were with a BR7ES which was a lighter color but the bike ran like crap. If it is jeeting related it is way to rich, my plugs wont last over 30 miles and that is with mostly back roads 1/4-3/4 throttle, very little start stop.

I will report back later this weekend with what i come up with, hopefully the rain holds off... they are calling for it all weekend into next week.

[Vince]

     A leak down test checks sealing of the rings and valve seats. The fluid  method you mentioned won't work for guides. Of course it will run out the bottom. The guide has clearance. Of course it will dribble down.  A quick test to INDICATE a potential valve seat problem is to fill the port with oil and see if it leaks around the valve seat. Call me (toll free:866-VINCEMC) and I will walk you through the leak down test procedure.

[JordanMix]

thank you. If i end up ordering the kit and picking up a compressor i will give you a call next week.

thank you everyone for all the help, i would have tossed in the towel along time ago if it wasent for everyone on all the different boards for RE's.

[Foggy_Auggie]

I've got a 2 gallon air compressor.  Works great for car and small truck tires.  Almost too much for motorcycle tires - the air chuck has so much pressure behind it a motorcycle tire valve stem won't release the chuck valve.

I use a hand pump on motorcycle tires.

No electrical power issues - 3 prong grounded plug.

A 2 gallon compressor should be fine for leak down testing.

[JordanMix]

It rained pretty bad here most of the weekend but I was able to switch out my main jet and put in a 125 and I also put the small baffle back into my “shortty” style exhaust… it is just to loud without it, its still pretty loud.

I did a plug chop in 3rd gear, going up a hill about 35 miles an hour and I had a really nice light brown so I was pretty happy with that. Once I got back into town I pulled the plug and it was black.


It is nice out today so when I get home from work I am going to try out a 27.5 pilot jet and see if that helps out at all with my lower speed fouling. Is lower speed fouling just something one should live with and expected it to be burnt off when you give the bike a good amount of throttle?

Is it possible that I am getting oil blow by and with the 125 main jet the engine was running so hot it burned all the oil off before it could be deposited onto the plug? I just want to make sure I’m not chasing a ghost here with re-jetting.


Since my rebuild all the plugs I have pulled have been black on the insulator (the whole part) the nose/center electrode, and the side electrode but none on the threads or the face of the top of the threaded part. Most pictures I see with wet/dry fouling have a lot of carbon or burn oil in this area.

[REpozer]

 I use a 150 PSI, 15 Gal, 1.5 HP compresser, It works fine for air tools but I wouldn't go smaller if that is a consideration.

[JordanMix]

i did not purchase a compressor this weekend... i think i am going to hold off. I am renting a house now and the garage just dosent have enough juice running to it to power anything big. We are going to buy or build within the next 2 years. I am just going to hold off and buy a large compressor at that time when i can run adequate electricity to a garage if it is not already avaiable. though having even a small one now would be nice.

[REpozer]

Good deal, another ideal would be to possibly buy the leak down tool from Harb freight and get you bike to , or borrow the air you need for the test. Hope it works  out.